The forming of various objects by molding is well known. Objects may be formed from various plastics and metals, such as by injection or compression molding, casting, etc., using an appropriate mold. There is frequently a stationary and movable mold half, and more complex molds may include one or a plurality of stationary and/or movable cores. The mold is located in a molding machine, which is responsible for opening and closing the mold and, commonly, for supplying the molding material to the mold.
Metallic parts are frequently formed via a specialized metal molding process. One such process is metal die casting, where molten metal is introduced into a closed mold (die) and allowed to cool to a point where the die may be opened and the formed part may be removed. A casting die may include a stationary core and a plurality of movable cores that are brought together to form a closed die. These cores may be used to form certain part features such as openings, voids, etc. Frequently, some or all of such cores may be sand cores.
The die casting process also includes the use of a die casting machine. The die casting machine serves many functions, including supporting and opening/closing the casting die, providing the molten metal to the casting die, ejecting the cast part, etc.
With respect to such die casting processes, problem may result when there occurs a non-uniform opening of the casting die. For example, if a movable core does not separate evenly from and/or is not retracted evenly from the stationary core and/or other movable cores, damage may result. The types of resulting damage may include, without limitation, galling or other deformations or breakage of the cast metal part, and cracking or breaking of one or more of the aforementioned sand cores that are frequently used to create certain part features in the cast metal part.
An uneven opening of the casting die may have several causes. One such cause is an uneven application of opening force to one or more of the moving die cores. As can be seen in FIG. 1, many die casting machines transfer the moving die cores between an open and molding position by one or more hydraulic cylinders. In the particular example shown in FIG. 1, two hydraulic cylinders are used to transfer the right-most moving die core 20 between a retracted position (shown) and a casting position where the die core 20 is in contact with other die cores 15, 25, 30, 35 that collectively form the casting die 10. It should be readily apparent that in a die casting machine of such a design, an imbalance in the hydraulic force exerted by these cylinders can also result in a non-uniform opening and movement of the associated movable die core 20.
One skilled in the art would understand that die casting machines are typically provided with tie bars, bushings and/or other guiding means that help to maintain even, linear travel of a movable casting die core. It has been found, however, that such guiding means cannot always sufficiently prevent the uneven opening of a casting die—especially when such an uneven opening results from an imbalanced application of hydraulic die opening force as described above.
Consequently, it can be understood that there is a need for a device that can prevent the uneven opening of a casting die—or of a non-die casting mold having a similar structure. Preferably, such a device would be cost-effective to produce and easy to install to a die casting machine or other molding machine of interest. Die Brace embodiments of the invention satisfy this need.